Electromagnetic brake



F. o. cLlzBE ELECTROMAGNETIC BRAKE Feb. 5,A 193s.

Filed Feb. 10, 1953 2 Sheets-Sheet l v Feb. 5, 1935. F. o. .cLlzBE 1,989,740

ELECTROMAGNETIC BRAKE l l Filed Feb. 10, 1933 2 Sheets-Sheet 2 Patented Feb. .1935 i UNITED STATESA PATENT OFFICE Applicationlh iose; 119,656,084

The present invention relates generally to elec- A further object of the invention is to protromagnetic brakes. More particularly, the invide'an electromagnetic vehicle brake in which vention relates to that type of electromagnetic the electromagnet is so constructed and so brake which is adapted primarily for use in conmounted with respect to the ring-shaped element 5 nection with one of the road-wheels of a vehicle which forms the power-multiplying connection 5 and comprises a brake drum on the wheel, a shoebetween the element and the brake shoes that in like electromagnet which is disposed in the drum conjunction with the element, it effects a quick and is adapted when energized to be attracted and forceful shift of the brake shoes into their to, and to rotate with, the drum, and a pair of braking position;

v brake shoes which arealso disposed in the drum A still further object of the invention is the 10 and are actuated into engagement or braking provision-of an electromagnet which is adapted contact with the inner periphery of the drum in elciently and eiectively to serve as the actuating response to rotation of the electromagnet with medium of a brake of the character under conthe drum. sideration and is of new and improved construc- One object of the invention is to provide an tion. l5 electromagnetic brake of this type which is more In addition, it is contemplated as one of the eilicient and positive in operation than previously objects of the invention to provide an electrodesigned brakes of the same general design by magnetic brake of the type under consideration virtue of the fact that the brake shoes are pivwhich is generally of new and improved construcotally mounted on fixed studs so as to swing outtion, may be manufactured at a low and reason- 20 wardly into contact with the inner periphery 0f able cost, contemplates operation of both brake the drum and are actuated into their braking shoes regardless of the direction of travel of the position in response to rotation of the electroroad-wheels and is an improvement upon that magnet with the drum by means of a direct exhibited in United States Letters Patent No.

power-multiplying connection between the mag- 1,783,280 granted to me December 2, 1930. 25 net and the shoes. `Other objects of the invention and the various Another object of the invention is to provide advantages and characteristics of the present a brake of the` last mentioned character in which brake construction will be apparent from a conthe power-multiplying connection for swinging or sideration vof the following detailed description.

shifting outwardly the brake shoes into braking The invention consists in the several novel 30 engagement or contact with the inner periphery features which are hereinafter set forth and are of the drum consists of a ring-shaped element more particularly defined by claims at the conwhich is disposed in and is concentrically posiclusion hereof. tioned with respect to the brake drum, is con- In the drawings which accompany and form a nected to the electromagnet so that it rotates part of this specication or disclosure and in 35 therewith when the latter is energized and emwhich like numerals of reference denote correbodies rollers which engage cam surfaces on the spending 'parts throughout the several views: brake shoes and cooperate therewith to actuate Figure 1 is a. vertical,` longitudinal, sectional the brake shoes into their operative position in view of an electromagnetic brake embodying the 40 response to rotation of the ring-shaped element invention, the various parts of the brake being 40 by the electromagnet. A l shown in their inoperative position.

Another object of the invention is toA provide Figure 2 is a similar sectional view showing an electromagnetic vehicle brake of the type and the parts of the brake in their operative or brak- Y character under consideration in which the ringing position;

shaped element which constitutes the direct Figure 3 is a vertical transverse section taken 45 power-multiplying connection between the elecon the line 3-3 of Figure 1 and showing in detromagnet and the brake shoe is of such 'diameter tail the cross sectional construction of the ringand construction thatthe entire inner portion of shaped element which forms the power-multiplythe brake drum is free and unobstructed. ing connection between the electromagnet and Another object of the invention is the provision the brake shoes; 50

in an electromagnetic brake of the character Figure 4 is an enlarged horizontal section taken hereinbefore specied of a novel spring arrangeon the line 4 4 of Figure 1 and illustrating the ment forretracting the ring-shaped element and construction and arrangement of the rollers the brake shoes to their inoperative positions which are mounted on the ring-shaped element when the electromagnet is deenergized. and operate in conjunction with'the cam sln'faces 5v on the brake shoes and in response to rotation of the element by the electromagnet, to shift the brake shoes into their operative or braking position;

Figure 5 is an enlarged vertical, transverse, sectional view takenon the line 5-5 of Figure '1, ex-k hibiting the lconstruction and arrangement of the electromagnet and the manner in which it is connected to the ring-shaped element; and

Figure 6 is a perspective of the magnet.

"The electromagnetic brake which forms the subject matter of the invention comprises a metallic drum 6 and is adapted primarily for use in cen# nection with a vehicle road-wheelW= The latter, as shown in Figure 3 of the drawings, is asso# ciated with lan axle A and consists of a hub H and a plurality of spokes S. 'Ihe axle A extends horizontally and is mounted rotatably in a bearing B which is attached to and forms a partof the chassis of the vehicleto which the brake is applied, and embodies a circular plate P inwardly 'of the wheel W. The hub of the 'wheel is splined or otherwise iixedly secured to the outerend of the axle A and is provided with a radially extending iiange F to which the inner ends of the spokes are secured and from which the spokes radiate, as well understood in the art.

The brake drum 6 is cylindrical and is positioned between the plate P and the inner side of the wheel W. It is c-f substantially the same diameter as the plate P and is secured fixedly to the wheel by way of a side plate 7 which is formed integrally with the drum and fits against and is secured to the inner ends of the spokes S. The central portion of the side plate 'I is attached to the hub H and is apertured so as to permit the axle A to pass therethrough. The plate P on the bearing B closes and forms a side for the inner side of the drum 6. The side plate 7 closes the other side of the drum and forms a connection whereby the drum 6 is driven or vrotated with the wheel W.

u In addition to the drum 6, the brake com- I prises a pair of brake shoes 8 and an electrothe studs.

'from the brake drum is restricted or limited by magnet 9. 'I'he shoes 8 extend substantially vertically and are positioned one directly opposite the other in the drum They are curved conformably to the inner periphery of the brake drum and have on the outer faces thereof brake linings 10 for engagement with the inner periphery of the drum. 'I'he lower ends of the brake shoes embody inwardly extending lugs 11 and are pivotally eonnected by these lugs to horizontally extending studs 12 so that they are free to swing outwardly into contact and braking relation with the inner periphery of the drum. `The studs 12 are anchored to, and project outwardly from the plate P of the bearing B and hold the brake shoes against rotation re1- atively to the brake drum. They extend thro-ugh the lugs 11 on the lower ends of the brake shoes and are connected at the outer ends thereof to an annulus 13 of non-magnetic material. The latter, as shown in Figures 3 and 5, is consentrically positioned with respect to the brake drum 6 and serves to hold the brake shoes against transverse displacement with respect to Swinging of the brake shoes to and means of a pair of pins 14. The latter are secured iixedly to, and project outwardly from, the plate l? of the bearing B like the pivot studs 12, and extend through elongated slots 15 in the central portions of the brake shoes. These slots are slightly curved and in conjunction with the pins 14 permit of limited Swinging of the brake shoes to and from the inner periphery of the drum. The outer ends of the pins are connected to the annulus 13.

The electromagnet 9 is in the form of a soft iron shoe and is positioned in the brake drum between the upper ends of the brake shoes 8. It is curved conformably to the inner periphery of the brake drum and is cut away so that it embodies a groove 9 extending longitudinally therearound. This groove is preferably of the character shown in Figure 5 and serves to form applied. When cinerent ows through the wire coils, the magnet is energized, and is attracted to the drum 6. 1f the wheel W is in rotation, the electromagnet, because of its adherence to the brake is rotated in the direction of rotation of the wheel. This rotative movement of the magnet is utilized to effect shift of the brake shoes into their operative or braking position, as hereinafter described. When the magnet is energized, a bipolar magnetic field is established because'of the construction or' the magnet, and the drum forms or operates as the yoke of the magnetic field. By virtue of the fact that the core piece of the magnet is comparatively long and the portion of the drum which serves as the yoke of the magnetic eld is small in comparison, maximum adhesion ef the magnet to the drum is obtained with a minimum amount of current. 'I'his feature is of considerable importance as far as the operation of the drum is concerned, inasmuch as the electrical system of an automobile is of comparatively small voltage and amperage.- The core 1'? is preferably formed so that it is nearer the inner edges of the pole pieces 9 than the outer edges. As aresult of positioned c'oncentrically with respect te, the' brake drum 6 and is of channel formation. It consists of a cylindrical base 20 and a pair of outwardly extending radial side anges 2i and is preferably formed of non-magnetic material.

The side flanges 21 are preferably formed integrally with the base 20 of the element and embody at the upper or top portions thereof circumferentially elongated extension-ns 22 for supporting the electromagnet 9. The magnet, as

shown in Figures 3 and 5, is positioned between these two extensions 22 and embodies at the ends thereof transversely extending pins 23. 'I'he ends of these pins extend through elongated slots 24 in the ends o f the extensions 22 and form with the slotted portions of the extensions between the magnet and the extensions, sliding connections whereby the magnet is supported so that it is free to move radially into and out of engagement with the inner periphery of the brake drum 6. The slots 24 ere preferably of such length that the movement of the magnet to and from the drum is limited to a comparatively small distance;

'I'he magnet is 'normally held in its inoperative position wherein it is out of contact with the inner periphery of the drum, by means of a pair of leaf springs 25. These springs are centrally supported by way of brackets on the outer faces of the elongated extensions 22 and are arranged so that the ends thereof b ear against the ends of the pins 23. When the'electromagnet 9 is energized, it is attracted to the drum and moves outwardly into contact with the drum against the combined force of the springs 25. When the magnet is deenergized, the springs which, as previously pointed out, are applied to the ends of the pins 23, shift the magnet downwardly into its inoperative position. The pins 23, together with the slotted' portions of the extensions 22, in addition to forming sliding connections between the magnet and the extensions, connect the magnet to the ring-shaped element 19 so that the latter is rotated by the magnet in response to rotation of the magnet with the drum. The element 19 is rotatably supported within the drum by means kof the pivot studs 12 for the brake shoes and a pin 26. This pin is xed to, and projects outwardly from. the plate P ofthe bearing B and is positioned directly beneath the electromagnet 9. It extends through arcuate slots 27 in the inner portions of the extensions 22 and is connected at its outer end to the annulus 13 which operates to hold the element against transverse or lateral displacement with respect to the pin. The slots 27 are concentrically positioned with respect to the axis of the wheel W and hence permit the element to rotate about the wheel axis. .The lower portions of the side iianges 21 of the ring-shaped element rest upon the pivot lugs 12, asshownparticularlyinFiguresZands of the drawings, so that these studs in conjunction with the pin 26, operate to support the element for rotative movement.

In order to eiect outward shift of the brake shoes in response to rotation or turning of the magnet with the -brake drum, the ring-shaped element 19 is provided at-diametrically opposite points with a pair of rollers 29. These rollers are positioned directly opposite the central portions of the brake shoes, as shown. in Figuresl and 2, and are mounted ArotatabLv on pins 30. The latter extend through Valigned holes or apertures in the side anges 21 of the ring-shaped element 19 and support. the rollers between the side lianges. I'he ends of the pins 39 are provided with washers 31 which areheld in place by cot- Vring-shaped element 19. Because of this fact.

thesurfaces33areinthenatureofcamcr -wedge surfaces and coact with the rollers 29 to eiect outward shift of the brake shoes in response to, rotation of the ringelement 19 in either direction. When the ring-shaped element 19 is in its inoperative position, the rollers are positioned centrally with respect to the surfaces 33 and inthis position exert no outward thrust or pressin'e on the brake drum. When the element 19 is rotated in response to turning or rotation of the magnet with the brake drum, the rollers 29 roll towards the end portions of the slnfaces 33 and as the result of the cam or wedge formation of the surfaces, shift the brake shoes outwardly into contact or braking engagement with the inner periphery of the drum. The arrangement of the rollers and cam surfaces is such that the outward movement of the brake shoes is comparatively small in proportion to the rotative movement of the magnet. With this arrangement, the necessary leverage is obtained eiectively and positively to brake the drum by the rotative movement of the magnet in response to drum rotation. The ring-shaped element 19 together with the rollers 29 and the wedge or cam surfaces 33 on the brake shoes exemplify a pwer-multiplyng connection whereby outward shift 0f the brake shoes is effected in response to rotation of the electromagnet with the drum. By virtue of the fact that the element 19 is ring-shaped, the cenh'al portion of the brake drum is free and unobstructed.

'I'he ring-shaped element 19 is retracted to its inoperative position when the magnet is deenergized by meansof a pair of tension springs 34 and 35. The spring 34 extends between and is connected to one of the pivot studs l2 and a pin 36 on the element 19, and serves to retract the element after rotation thereof in one direction. The spring 35 extendsbetween theiother pivot stud 12 and a pin 3'7 on the element 19 and operates to retract the element when it is rotated in the opposite direction. The two springs 34 and 35 extend in opposite directions and are applied to the central portions of the pivot lugs 12. 'I'he pins 36 and 37 extend transversely with respect to the ring-shaped element 19 and project through and are in aligned apertures or holes'in lthe side 2l. The brake shoes 8 are returned to their inoperative position upon release of the ung-hemd element 19 by means of a pair of tension springs 33. These springs extend between and are connectedto the guide pin 26 andthe upper or distal ends of the brake shoes 9.

The operation ot the brake is as follows:

Whenitisdesiredtobrake thewheel W to which the brake is applied, electrical current or energy is supplied to the wire coils 18 around the corerpieces 17 so as to energize the magnet 9. The magnet, as soon as it becomes energized,

moves outwardly into contact with the brake During the raking operation, the magnet slides with respect to the' inner periphery of the drum, but because 0f its attraction to the drum, sets up sumcient torque or angular movement as far as the rinsvshped element 19 is concerned, to effect the proper outward thrust of the brake shoes through the medium .oi the rollers 30 and the surfaces 33. When .the electric current or energy is cut oi! and the magnet becomes deenergized. the leafsprings at the sides of the elongated extensions 23 shift the magnet downwardly away from the linner periphery of the brake drum. At the same time,

the springs .25 shiftdownwardly orI retract the electromagnet 9, the springs 34 and 35 retract the ring-shaped element 19 to its inoperative position and the springs 38 swing inwardly the brake shoes 28 so as to break contact ofthe brake linings with the inner periphery of the brake dmm. Regardless of whether the wheel Wis rotating forwardly or rearwardly, shift of both brake shoes into contact or braking engagement with the drum is effected when the electromagnet is energized.

The herein described electromagnetic brake consists of but a small number of parts and hence may be manufactured at a low and reasonable cost. By virtue of the fact that the electromagnet actuates the brake shoes through a power-multiplying connection, braking of the drum is eiected quickly and positively.

Whereas the brake has been described as being adapted primarily for use in connection with one of the road-wheels of a veliicleit is to be understoodthat the brake may be used in other ways. It -is alsosto be understood that the invention is not to be restricted to the details set forth, since these may be modied within the scope of the appended claims, 'without departing from the spirit and scope of the invention.

Having thus described the invention. what I claim as new 'and desire to secure by Letters Paten is: I.,

1.\ InK an electric brake of the character described, the combination of a rotatable drum, a brake shoe mounted within the drum to swing on a fixed pivot into and out of braking relation with the drum, an electromagnet positioned in vthe drum and adapted when energized to be attracted to and rotated by the drum, and a power-multiplying connection for swinging the brake shoe into .braking relation with the drum. in response to rotation of the electromagnet, comprising an element rotatably mounted within the drum and connected directly to the electromagnet so as to rotate therewith, and coacting cam and roller means operable by rotation of the element for camming said shoe into its aforesaid braking relation with the drum.

2. In an electric brake of the character described, the combination of a rotatable drum, a.

brake shoe mounted within the drum to swing on a fixed pivot into and out of brakingrelation with the drum, an electromagnet positioned in the drum and adapted when energized to be attracted to and rotated by the drum, and a powermultiplying connection for swinging the brake shoe into braking relation with the drum in response to rotation of the electromagnet, comprising a ring-shaped element mounted rotatably in the drum and connected directly to the electromagnet so as to rotate therewith and coacting cam and roller means between the element and the shoe whereby the shoe is cammed into its braking relation with the drum upon rotation of the element with the magnet. f 3. In an electric brake of the character described. the combination of a rotatable drum, a

y brake shoe mounted in the drum and on a^xed pivct to swing laterally into 'and 'out of braking relation with the drum and having on the inner part thereof a wedge or-cam surface, an electro.

tromagnet, comprising an element mounted rotatably in the drum and connected to rotate with the magnet, and a member carried on the element arrangeed to engage the aforesaid surface on the brake shoe to swing the brake shoe outwardly into its braking relation with the drum upon rotation of the element.

4. In an electric brake of the character described, the combination of a rotatable drum, a

brake slfoe mounted in the drum and on a fixed pivot to swing laterally into and out of braking relation with the drum and having on the inner part thereof a wedge or cam surface, an electro'- magnet positioned in the drum and adapted when energized to be attracted to and rotated by the drum, and a power-multiplying connection for swinging the brake shoe into braking relation with the drum in response to rotation of the electromagnet, comprising an element mounted rotatable in the drum and connected to rotate with the magnet, and a roller on the element engaging the aforesaid cam or wedge surface on the brake Athe drum.

5. In van electric brake of the character described, the combination of a rotatable drum, -a pair of oppositely facing brake shoes in the drum mounted pivotally to swing outwardly'into braking relation with the drum and embodying cam or wedge surfaces on the inner parts thereof, an electromagnet disposed in the drum between contiguous or opposite ends of the brake shoes and adapted when energized to be attracted to and rotated by the drum, and a power-multiplying connection for swinging the brake shoes into braking relation withy the drum in response to rotation oi' the electromagnet, comprising a ringshaped element mounted rotatably in the drum and between vthe shoes and connected-to rotate with the magnet, and members carried on substantially diametrically opposite parts of the element and engaging the aforesaid cam or wedge surfaces on the shoes in such ahmanner as to cam or wedge the shoes outwardly against the brake drum upon rotation of the element.

6. In an electric brake of the character described, the combination of a rotatable drum, a pair of oppositely facing brake shoes in the drum mounted pfvotally to swing outwardly into braking relation with the drum and embodying cam or wedge surfacesl on the inner parts thereof, an electromagnet disposed in the drum between contiguous or opposite ends of the brake `shoes and adapted when energized to be attracted to and rotated by the drum, and a power-multiplying connection for swinging the brake shoes into braking relation with the drum in response to rotation of the electromagnet, comprising a ringshaped element mounted rotatably in the drum and between the shoes and connected to rotate with the magnet, and rollers carried on substantially diametrically opposite parts of the ringshaped element and mounted so that they engage the aforementioned cam or wedge surfaces on the shoes and coact therewith to cam the shoes outwardly .against the drum upon rotation of the element. v f

'1. In a brake, the combination of a rotatable drum, a pair of brake shoes positioned one opposite to the other within the drum and mounted pivotally to swing outwardly into braking relation with the drum. a member Adisposed in the drum between contiguous or opposite ends of the brake shoes and adapted to be shifted into contact with the drum for rotation therewith, a power-multiplying connection for swinging the brakes outwardly into braking relation with'. the drum in response to rotation by the member, comprising a ring-shaped element mounted rotatably in the drum and between the shoes and connected to rotate with the member, and coacting cam and roller means between the element tion with the drum and having cam or wedge surfaces in the inner parts thereof, a member disposed in the drum between contiguous or opposite ends of the brake shoes and adapted to be shifted into contact with the drum for rotation therewith, and a power-multiplying connection for swinging the shoes outwardly into braking relation with the drum in response to rotation of the member with the drum, comprising a ring-shaped element mounted rotatablypin the drum between the shoes and connected for rotation with the member, and rollers carried by the element at substantially diametrically opposite points and arranged so that they engage the aforementioned cam or wedge surfaces and operate therewith to cam the shoes outwardly into engagement with the drum upo'n rotation of the element.

9..In a brake, the combination of a rotatable drum, a brake shoe in the drum pivotally supported so as to swing outwardly into braking relation with the drum and having a. cam or wedge surface in the inner part thereof, a member disposed in the drum between contiguous or opposite ends of the brake shoes and adapted to be shifted into contact with the drum for rotation therewith, and a power-multiplying connection for swingingthe shoe outwardly' into braking relation with the drum in response to rotation of the member, comprising a ring-shaped element mounted rotatably in the drum and connected to rotate with the member, and a roller carried by the element and engaging the cam or wedge surface on the shoe so as to cam the shoe outwardly against the drum upon rotation of the element.

10. In a brake, the combination of a rotatable drum, a pair of oppositely facing brake shoes in the drum pivoted to swing outwardly into braking relation with the drum and having cam or wedge surfaces on the inner parts thereof, and a powermultiplying connection for swinging the brake shoes outwardly into braking relation with the drum, comprising a ring-shaped element rotatably mounted in the drum between the shoes, and rollers carried by the element and engaging the surfaces so as to shift the shoes outwardly into contact with the drum upon rotation of the element.

1i. In an electric brake of the character described, the combination of a rotatable drum, a brake shoe mounted in the drum and arranged to move outwardly into braking relation with said drum, an electromagnet disposed in the drum and adapted when energized to be attracted to and rotated by the drum, said magnet being in the form of an elongated arcuate, metallic shoe and having a groove extending longitudinally therearound and forming laterally spaced pole pieces and a central core, and a wire coiled around the core so that the coils thereof extend parallel to and are positioned between the pole pieces,.

and means operated in response to rotation of the magnet with the drum for moving the brake shoe outwardly into braking relation with the drum.

12. As a new article of manufacture, an electromagnet for a brake of the-drum type, comprising an elongated, arcuate, metallic shoe adapted to operate against the inner periphery of the drum of the brake and having a continuous longitudinalv groove extending around the outer end and inner faces thereof and forming a pair of laterally spaced pole pieces and a core piece between the pole pieces, and a wire coiled around the core so that the coils thereof extend parallel to and are disposed between the two pole pieces.

FLOYD O. CLIZBE. 

